Assertion (A):
Transgenic animals are designed to serve as models for studying human diseases like Alzheimer's and Cystic Fibrosis.
Reason (R):
By introducing genes that alter the normal body functions, researchers can investigate disease development and test new treatment methods.

[Biotechnology-and-its-Applications] [class-xii ]

• (A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion
• (B) Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion
• (C) Assertion is true but Reason is false
• (D) Assertion is false but Reason is true
Correct Option: A  [ A ]

Remark: Transgenic animals are engineered to mimic human disease states (models exist for cancer, cystic fibrosis, rheumatoid arthritis, and Alzheimer’s). This allows scientists to study gene contribution to disease and evaluate new therapeutic interventions.

Assertion (A):
The Bt toxin only becomes active upon ingestion by an insect pest.
Reason (R):
The alkaline pH of the insect midgut solubilizes the inactive protoxin crystals, converting them into the active toxin form that binds to epithelial cells.

[Biotechnology-and-its-Applications] [class-xii ]

• (A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion
• (B) Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion
• (C) Assertion is true but Reason is false
• (D) Assertion is false but Reason is true
Correct Option: A  [ A ]

Remark: The Bt toxin exists as an inactive protoxin within the bacteria. The specific alkaline conditions in the insect gut are required to solubilize the crystals and activate the toxin, which then binds to the midgut epithelial cells, leading to lysis and death.

Assertion (A):
Tissue culture relies on the principle of totipotency.
Reason (R):
Totipotency is the capacity of any plant cell or explant to regenerate into an entire new, whole plant when grown *in vitro* in a special nutrient medium.

[Biotechnology-and-its-Applications] [class-xii ]

• (A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion
• (B) Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion
• (C) Assertion is true but Reason is false
• (D) Assertion is false but Reason is true
Correct Option: A  [ A ]

Remark: Totipotency is the inherent ability of plant cells to develop into a complete plant. This capacity is utilized in tissue culture, allowing the growth of whole plants from small explants under sterile, controlled conditions.

Assertion (A):
Genetically modified organisms (GMOs) are regulated by the GEAC in India.
Reason (R):
The GEAC was established to evaluate the morality, validity, and safety of introducing GM organisms into the public sector due to the potential for unpredictable ecological results.

[Biotechnology-and-its-Applications] [class-xii ]

• (A) Both Assertion and Reason are true, and Reason is the correct explanation of Assertion
• (B) Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion
• (C) Assertion is true but Reason is false
• (D) Assertion is false but Reason is true
Correct Option: A  [ A ]

Remark: Genetic modification raises serious ethical and biological questions, particularly regarding unpredictable outcomes in the ecosystem. GEAC (Genetic Engineering Approval Committee) oversees the research and public release of GMOs to ensure safety and validity.